As an ex military satellite communications engineer I certainly remember working with spread spectrum modulation and also frequency hopping technology in the 1980's. Wireless Local Area Networking technology today exploits a technology which was thitherto mostly hidden inside this shadowy domain of military communications and radar. This technology comprises a collection of ideas which are termed Spread Spectrum Techniques (SST). Spread Spectrum techniques have some powerful properties which make them an excellent candidate for networking applications. To better understand why, we will take a closer look at this fascinating area, and its implications for networking.

Space travel has and continues to fascinate us. As humans it will always be our intrinsic instinct to explore and discover whatever lies over the next horizon. Such was the motivation for the space race which ultimately provided the world with satellite communications amongst many other things. When we look back at the grainy pictures from that febrile time in history however what we see is a world which looks very different to that of today. Indeed most of the sci-fi of the 1960's was set around about now. As people of their future looking back it all seems rather quaint to us but the benefits we have enjoyed from satellite communications have been many and varied. Since the launch of Telstar, satellite communications has enabled us to beam the finger of mass communications to every corner of the planet

The above notwithstanding, our world today is criss-crossed by undersea cables between every continent and across every sea. Satellite communication (or SATCOM as we will refer to it moving forward) would seem to no longer be necessary... or is it? Lets take a look at the benefits it brought to us at its genesis.

Satcom is the ultimate mobile technology. It provides us with the possibility for cable free communications across the whole footprint of a beam. For some types of spacecraft such a footprint can cover many hundreds of thousands of square miles from only one beam. A single spacecraft can support many beams. That we can utilise this technology anywhere within the beam is such an enormous asset that it completely revolutionises our activity in the remotest areas of the planet. It is now possible to call your mum from a rowing boat in the middle of the atlantic ocean on mothers day, or indeed on any day. Such is the ease of use that is possible using technology no more byzantine than a satellite phone.

Satellite comms is also relatively cheap although the person who owns the satellite phone may ask you to keep it brief whilst calling your mum. Mobile terminals are however cheap and cheerful when examined in the context of global communication methods. They can also be quite easily adapted to support voice, video or data or indeed all three at once. It is being used extensively as a medium through which to deliver broadband internet services to difficult to reach areas within developed countries not to mention those with a less ubiquitous infrastructure. The frequencies used for satcom are selected specifically because of their ability to resist absorption enabling them to cover the enormous distances required. On top of this it is impossible to ignore the enormous usage of satellite for broadcast media such as television broadcasting where the system is set up primarily for one way communication. In summary then satellite communications has and continues to deliver enormous benefits and has a number of key unique selling points.

The premise of this post however does not seek to confirm the obsolescence of Satcom but rather to examine its place in the ever changing telecommunications landscape. In today's world of wireless communications, high definition television and global access to the Internet, many people are unclear about the inherent advantages of satellite communications but they persist and are many.

Cost Effective - The cost of satellite capacity doesn't increase with the number of users/receive sites, or with the distance between communication points. Whether crossing continents or staying local, satellite connection cost is distance insensitive.

Global Availability - Communications satellites cover all land masses and there is growing capacity to serve maritime and even aeronautical markets. Customers in rural and remote regions around the world who cannot obtain high speed Internet access from a terrestrial provider are increasingly relying on satellite communications.

Superior Performance - Satellite is unmatched for broadcast applications like television. For two-way IP networks, the speed, uniformity and end-to-end control of today's advanced satellite solutions are resulting in greater use of satellite by corporations, governments and consumers.

Immediacy and Scalability - Additional receive sites, or nodes on a network, can readily be added, sometimes within hours. All it takes is ground-based equipment. Satellite has proven its value as a provider of "instant infrastructure" for commercial, government and emergency relief communications.

Versatility and More - Satellites effectively support on a global basis all forms of communications ranging from simple point-of-sale validation to bandwidth intensive multimedia applications. Satellite solutions are highly flexible and can operate independently or as part of a larger network.

As we move froward and the need for ubiquitous communications becomes ever more embedded into the fabric of our lives, satellite communication will move into a golden age. Techniques and mechanisms with which to leverage the spacecraft as a communications platform are continually evolving and it is this swathe of new and exciting use cases that will take the communications satellite into the rest of the 21st century and beyond.

Ingenious new techniques such as that envisioned by companies like Leosat and OneWeb demonstrate that the traditional paradigm of teleport-satellite-teleport communications is no longer de rigeur. As new business models seek to create optical meshed networks in the sky, new uses continue to emerge. Such networks will ultimately become the fastest communication links for distances over 10,000 miles because light travels faster through a vacuum than it does through glass. For applications which need to shave every possible fraction of a second from network delays (and there are many) these new networks will surpass the existing terrestrial networks no matter how few routed hops are required. The high speed world of financial algo trading, where microseconds cost millions will quickly move to these types of networks once they reach production.

As we move slowly away from the turn of the 21st century some may have expected that satellite communication may have been headed for its swansong given the ubiquity and reach of terrestrial networks. I'd appreciate your thoughts in the comments section below as to what the future may hold for satellite communication or indeed perhaps more broadly for spacecraft communication. I think its fair to say that reports of its demise have been greatly exaggerated.

The Civil Aviation Authority has shortlisted Campbeltown, Prestwick and Stornoway airports to host the UK’s first spaceport, after narrowing down the field of possible locations to five in a consultation. Prestwick Airport, currently owned by The Scottish Government, and a strategically positioned airport on the Clyde Estuary coast in Ayrshire welcomed todays announcement from Westminster along with South Ayrshire Council which establishes the framework around which the selection of the first UK spaceport will be made.

One of the key drivers of the push is the well established notion that the country needs to have a fully operational Spaceport by 2018 in order to further vitalise the blooming UK space industry. The new location will become a centre of operations for the launch of new high tech instrumentation and satellite based technology and vehicles. Furthermore it may well become a major technological hub for all UK companies involved in the space industry providing launch and maintenance facilitiues for such companies as Virgin Galactic and Spacex.

Iain Cochrane, Chief Executive of Glasgow Prestwick Airport, said: "Prestwick Airport has been a pioneer of the UK aerospace industry and aviation since its foundation in 1935. I believe Prestwick offers the perfect conditions for space launches and our extensive developed concrete airfield and 3km runway provide the facilities needed for all types of re-usable spacecraft in development.

"We have an experienced high-tech aerospace workforce and a substantial aviation and high-tech engineering industrial footprint. Our Scottish Enterprise incentive zone supports the growth of the space industry. Our universities in Glasgow and Ayr are at the forefront of space and aerospace engineering research and teaching. While we have safe over-water flight paths, we also have over 4m people within a 2 hour drive giving us access to the widest range of specialists and expertise. This combination of features is unique amongst the sites being considered and positions Prestwick as the leading candidate to become the UK's first Spaceport."

Andrew Miller, Chairman of Glasgow Prestwick Airport, said: "Winning the Spaceport for Scotland and Prestwick will create a platform for revenue growth and industrial development for the next thirty years and more. It is a truly strategic development that will underpin jobs and growth regionally and nationally. Prestwick is the only site that can release this potential. It will drive transformational change both at the airport and local level and also in Scotland and the UK as a whole."

Prestwick Spaceport Director Stuart McIntyre said: "We have been working hard to structure our programme since the consultation programme closed last October. We have a detailed understanding of what is required and have already begun our bid preparations.

"We have secured strong support from our stakeholders in the region as well as internationally. We are determined to offer the global space industry a highly capable facility that will exploit Scotland's perfect location for polar orbit launches and space programme research and development. Prestwick will sit at the heart of an end-to-end space industrial capability allowing commercial space application developers to realise their designs, launch them to orbit and distribute their service to their global customers."

Councillor Bill McIntosh, Leader of South Ayrshire Council and Chair of the Glasgow Prestwick Airport and Aerospace Stakeholder Group, applauded Prestwick's bid: "Glasgow Prestwick Airport has extensive developed facilities and the ideal infrastructure and resources to deliver a first-class spaceport for the UK. This includes a significant amount of land for aerospace and spaceport industries. With direct motorway access, we are less than half an hour from Glasgow and easily accessible from all parts of the UK – you really couldn't ask for anywhere better to fulfil this important role. Aerospace is a major part of our lives in Ayrshire and we look forward to making the Glasgow Prestwick spaceport a reality and welcoming the space industry to this wonderful part of the world."

The UK Government selection programme is expected to run until October 2015 with Prestwick one of the possible locations being considered alongside Newquay in Cornwall, Llanbedr in Wales and a number of alternative Scottish sites.

It is important to have a clear line of sight between the antenna and the satellite.

In the latitudes of the planet closer to the poles, the lower antenna elevation angles required increase the likelihood of obstructions on the ground coming between the antenna and the satellite. The calculator below displays the distance the antenna needs to be from a potential obstruction in order to ensure a clear line of sight for a given elevation.

This tool can be used for all obstacles from trees near a house to mountains in the distance.